1. Field of the Invention
The present invention relates to peripheral input devices for a computer. The invention concerns, more particularly, an input device that senses angular displacement of the input device relative to a support surface. The invention has application to moving a pointer image, such as a cursor, relative to a computer display or scrolling an image relative to the computer display, for example.
2. Description of Background Art
As the field of computer science has matured, a variety of peripheral input devices have been developed to facilitate the use of computer systems and the entry of information into computer systems. One particular type of input device is conventionally referred to as a pointing device. Examples of pointing devices include a mouse, touchpad, trackball, and stylus, for example. Among other functions, a pointing device is utilized to move a pointer image, such as a cursor, relative to a display screen. More particularly, movement of the pointing device or a component associated with the pointing device generates position data corresponding with the movement of the pointing device. The position data is then transmitted to the computer system and processed by the computer system so as to be rendered on the display screen as movement of the pointer image. By utilizing the pointing device, therefore, the user can move the pointer image to a desired location on the display screen. A command key on the pointing device can then be activated to manipulate data or other images rendered on the display screen.
Many traditional display screens permit only a single data file, such as a text document, digital photograph, spreadsheet, or Web page, to be conveniently displayed as an image on the display screen. When configuring a conventional pointing device for use with a traditional display screen, the user balances the velocity of the pointer image with the accuracy of movement of the pointer image. In general, the velocity of the pointer image is inversely-related to the accuracy of movement of the pointer image. Accordingly, an increase in the velocity of the pointer image engenders a corresponding decrease in the accuracy with which the pointer image may be placed at a desired location. For this reason, the user generally configures the pointing device to move the pointer image at the highest velocity that also permits the pointer image to be accurately placed in a desired location on the display screen.
In contrast with many traditional display screens, a modern display screen may exhibit significantly greater dimensions and resolution, which permits relatively large quantities of data to be rendered. When configuring a conventional pointing device for use with a modern display screen, the balance between the velocity of the pointer image and the accuracy of movement of the pointer image remains relevant. Accordingly, the user generally configures the pointing device to move the pointer image at the highest velocity that also permits the pointer image to be accurately placed in a desired location on the display screen. Although this balance between velocity and movement is suitable for working with a relatively small, traditional display screen, the user may find that the velocity is insufficient to efficiently permit the user to move the pointer image between areas that are separated by a relatively large distance on the relatively large, modern display screen. Accordingly, the velocity of the pointer image may not be sufficient to efficiently move the pointer image from one portion of the display screen to another portion of the display screen.
When using a mouse, for example, with the relatively large, modern display screen, the user may be required to perform multiple movements of the mouse to cause a desired movement in the pointer image. For example, translating the mouse across the width of a support surface may only move the pointer image a portion of the desired distance on the display screen. The user may then be required to repetitively lift the mouse from the support surface and reposition the mouse on the support surface to induce additional movement in the pointer image. Similarly, multiple movements of a trackball may be required to cause a desired movement in the pointer image.